The Lactate Curve

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What is the lactate curve? Why do I need to know the lactate curve? How does it fit into my triathlon training? When should it fit in my triathlon training? How does it affect my triathlon racing? What does the lactate curve mean to endurance athletes?

Peter Jannsen answers many of these questions in his book, “Lactate Threshold Training.” An excerpt follows that will likely wet your appetite to learn more about how it can help your racing.

lactate threshold training“The lactate content of the blood is a parameter of great importance. This content is measured in millimoles of lactate per liter of blood. Healthy persons at rest have values roughly between 1 and 2 millimoles per liter, and strenuous exercise increases this value. Even slight increases in lactate content (6 to 8 millimoles per liter) may impair an athlete’s coordination. Regularly high lactate values impair aerobic endurance capacity.

THE LACTATE CURVE
For this reason, athletes should be prudent with the number of intensive workloads they undergo in a certain period of time. The workload intensities needed for various workouts can be determined by means of the lactate curve. Graph 89 shows the relationship between lactate content of the blood and the intensity of exercise. Intensity is expressed as running pace in meters per second.

To obtain a lactate curve, the athlete should run the same distance a number of times, each time at a higher pace. After every run, determine the lactate concentration in the blood. Every distance should be run at an even pace, and the running pace should be increased in small steps. The length of the run should be such that the athlete needs at least 5 minutes to cover the distance. When well-trained athletes run slowly, they have low lactate values; their energy supplies are fully aerobic. When the pace is increased, the curve begins to rise; the working muscles do produce lactate, but the quantities are so small that, for the most part, they can be neutralized by the body. It is a widespread belief that this is the case between 2 and 4 millimoles per liter. Therefore, this area is called the aerobic-anaerobic transition zone.

Each athlete can maintain a certain running pace for a long period of time without lactate accumulation in the body. If the pace is increased to a certain point, ongoing acidosis will occur, depending on the degree and duration of the increase, and at a certain moment this acidosis will force the athlete to stop. The lactate content that is measured at this borderline pace is also called the anaerobic threshold. The anaerobic threshold value is around a lactate content of 4 millimoles per liter. Exercise surpassing the anaerobic threshold will inevitably increase lactate content within the body.

Thus, exercise up to this level of the aerobic threshold is fully aerobic. Lactate content at the aerobic threshold is about 2 millimoles per liter. Exercise within the aerobic-anaerobic transition zone is more intensive, and energy supply is both aerobic and anaerobic. Production and neutralization of lactate are balanced. This zone is between 2 and 4 millimoles per liter.

The anaerobic threshold occurs when exercise at a high intensity results in an accumulation of lactate in the blood. Therefore, this type of exercise can be maintained for a limited period of time. But at an intensity just below the anaerobic threshold, this lactate content can be kept at a steady-state level, and this type of exercise may be maintained for a longer period of time, about 1 to 1.5 hours.

Lactate content at the anaerobic threshold is for many athletes about 4 millimoles per liter, but there are wide individual variations among athletes. Anaerobic threshold can be as low as 2 to 3 millimoles per liter or as high as 6 to 8 millimoles per liter. By drawing a lactate curve for every athlete, the anaerobic threshold can be found and subsequently used to set training intensities. The best way to find the anaerobic threshold is to determine maximal lactate steady state (MLSS), which is discussed elsewhere in the book.

Endurance capacity can best be trained by endurance workouts around the level of the anaerobic threshold, that is, workouts with lactate values of 2 to 6 millimoles per liter. These values may be determined according to the athlete’s test results. Very well-trained people mostly train their endurance capacity at somewhat lower values, between 2 and 3 millimoles per liter. Less well-trained persons often cannot help but peak to higher levels. They then surpass their anaerobic threshold and make their workouts less effective. Though they often feel satisfied with a strenuous workout, this type of workout does more damage than good.

The threshold pace is the speed that corresponds with the anaerobic threshold. Above the anaerobic threshold this speed can be maintained for a short period of time, but below the threshold it can be maintained 1 to 1.5 hours. The threshold pace, the running or cycling speed at the heart rate deflection point (HRdefl), is also called the V4 pace, as discussed in chapter 3. However, the term V4 is somewhat misleading, because many athletes have an anaerobic threshold over or under 4 millimoles per liters. For example, an athlete with an anaerobic threshold of 6 millimoles per liter could be said to have a threshold pace of V6.

Sport-specific performance capacity could be defined as the speed that is reached at a lactate content of 4 millimoles per liter, or V4. V4 is an important indicator of the athlete’s capacities. Any improvement of V4 pace will also improve performance capacity. Regular V4 tests indicate the athlete’s condition, so athletes can be monitored in their development and can be mutually compared. But remember that V4 is not the threshold pace for everybody, because many athletes have an anaerobic threshold under or over 4 millimoles per liter. Therefore, it might be better to test MLSS than V4.

Recovery workouts should not be intensive, and lactate content should remain less than 2 millimoles per liter. Intensive interval workouts give high lactate values, far surpassing 4 millimoles per liter. The effect of training will be that the lactate curve shifts to the right, as shown in graph 90.

Therefore, training intensities should be readjusted from time to time, and a new test procedure with blood sampling will be necessary. Not every athlete has access to blood testing, but other methods can supply the same or at least the most important information. All these other methods of finding the anaerobic threshold are discussed elsewhere in this book.”